Lollapalooza is known as much for its music as it is for costly park damage, outlandish happenings and surprise attendees.

But it's also known for all the under-21s who attend, and the smorgasbord of drugs and booze ingested during the three-day festival in Grant Park.

So findings released Monday by a team of doctors at Lurie Children's Hospital showing a spike in intoxicated teen girls visiting the hospital's emergency room on Lolla weekend should not shock anyone.

"We hear about Lollapalooza concert-goers damaging the grass in Grant Park but we never hear about the binge drinking among underage drinkers," Dr. Robert Tanz, a pediatrician at Lurie and pediatrics professor at Northwestern University, said in a statement announcing the study. "Teenage binge drinking at this festival is definitely a public health issue."

Officials with the hospital will present their findings Monday to the Pediatric Academic Societies conference.

Dr. Sarah McAndrew, a chief resident at the hospital, said the study does not seek to frame its findings as an earth-shattering revelation.

Rather, she said, it's about raising awareness among parents and other health care providers.

"Everything starts with the parents, and making them more aware," she said.

The fact that many of the drunk festival attendees who visited the ER last summer were teen girls raises other concerns as well, McAndrew said.

Lurie Children's researchers compared the number of emergency room patients during Lollapalooza weekend 2014 with four control weekends — two just before and two after. On the control weekends, there was an average of 69 patients. During Lollapalooza weekend there were 84, including 31 who said they had attended Lollapalooza. The hospital tested 26 of those 31, and every one had a blood alcohol level above 0.08, according to the study.

The patients from Lollapalooza were more likely to be female. During the control weekends, half of the patients were female. But more than two-thirds of the patients who said they came from Lollapalooza — 22 of 31 — were female.

Teens also accounted for a greater proportion of ER patients (25 percent) during Lolla weekend compared with 19 percent during the other weekends, according to an abstract of the study.

"However they are getting the alcohol, parents need to be aware of their teenager's behavior," Tanz said.